Many currently manufactured vehicles incorporate hydraulic braking systems, and those systems use a brake fluid to transmit pressure from the controlling mechanism to the braking mechanism of a vehicle. A hydraulic braking system generally includes a brake pedal or brake lever, a push rod (known as the actuating rod) having an end connected to the brake pedal, a brake master cylinder having a piston assembly connected to the push rod, and a brake caliper assembly having brake pads and a rotor/drum attached to an axle of the vehicle. The working brake fluid is generally ethylene glycol, though alternative suitable fluids are also used.
During operation of a hydraulic braking system, as the brake pedal is pressed, the push rod exerts a force on the piston of the master cylinder, which causes brake fluid to flow out from a brake fluid reservoir to the hydraulic lines of the braking system. That action increases pressure in the brake lines, which in turn forces pads on the brake calipers to close against a spinning rotor, generating a braking torque. Similarly, as the brake pedal is released, the piston of the brake master cylinder retracts to its original position, which relieves the pressure on the brake caliper pistons, thus, eventually releasing contact of the brake pads with the rotor.
If air is present in the brake fluid circuit, as will happen if the braking system is not accurately filled with brake fluid, the driver may experience a spongy brake pedal sensation while applying the brakes. In such cases, depending on the volume of air present in the braking system, the brake pedal or the brake lever may be even pushed to the stop without experiencing much resistance. To address this problem, the air present in the hydraulic lines must be evacuated.
When a vehicle is manufactured, the braking system is generally tested using a “pedal checker”, which measures the distance travelled by the activation device (i.e., the brake pedal or the brake lever) with respect to the activation force required to achieve the distance travelled. A pedal checker is an external device installed within a suitable portion of a vehicle, such as the seat rail. While testing braking systems of multiple vehicles assembled and manufactured in series along an assembly line, testing the hydraulic braking system of each of those vehicles through a pedal checker is cumbersome, as it may consume considerable amount of time to mount the pedal checker within each of those vehicles. Further, the sum of the mounting time for the pedal checker and the time consumed in recording test values for each vehicle (i.e., the pedal travel distance and the pedal force applied) should be synchronized with the cycle time of the vehicles at the assembly line, which is another problem. Another major disadvantage of a pedal checker is its unsuitability for use in repair facilities, due to the complexity of installation.
Considering the problems mentioned above, and other shortcomings in the art, there exists a need for a more effective method of testing the hydraulic braking system incorporated in a vehicle.